I keep finding plenty of 6l80e transmissions for cheap and included with them is a new awd transfer case, my questions are what is better the 4l80 or this new 6l80, is it essentially the same unit or is there changes internally? Anyone with good inside info please respond, Im planning on doing a swap into my Yukon Denali and I do plan on forced induction so I want a strong drive train since eveything I read says the 65 is not a good choice for my heavy suv with power.

 

Not sure what you call "cheap", but if you're planning FI on a heavy vehicle budget $3,000 to have CircleD build the 6L80 otherwise go with the 4L80.

 

The problem with the 6l80e is that you won't be able to control it with your computer.

You want to the 4l80e.

 

These are two totally different units. One is a six speed and the other is a speed. None of the parts are interchangeable.